It is possible that a module is breaking the device so bad that zygote
cannot even be started. In this case, system_server cannot start and
detect the safe mode key combo, set the persist property, and reboot.
Also on old Android versions, the system directly goes to safe mode
after detecting a key combo without rebooting, defeating the purpose of
Magisk's safe mode protection if we only check for the persist property.
Directly adding key combo check natively in magiskd allows us to enter
Magisk safe mode before the system is even aware of it.
When detecting device is booting as Safe Mode, disable all modules and
MagiskHide and skip all operations. The only thing that'll be available
in this state is root (Magisk Manager will also be disabled by system).
Since the next normal boot will also have all modules disabled, this can
be used to rescue a device in the case when a rogue module causes
bootloop and no custom recovery is available (or recoveries without
the ability to decrypt data).
Rewrite the whole module mounting logic from scratch.
Even the algorithm is different compared to the old one.
This new design focuses on a few key points:
- Modular: Custom nodes can be injected into the mount tree.
It's the main reason for starting the rewrite (needed for Android 11)
- Efficient: Compared to the existing implementation, this is the most
efficient (both in terms of computation and memory usage) design I
currently can come up with.
- Accurate: The old mounting logic relies on handling specifically every
edge case I can think of. During this rewrite I actually found some
cases that the old design does not handle properly. This new design is
architected in a way (node types and its rankings) that it should
handle edge cases all by itself when constructing mount trees.
Previously, we use either BroadcastReceivers or Activities to receive
messages from our native daemon, but both have their own downsides.
Some OEMs blocks broadcasts if the app is not running in the background,
regardless of who the caller is. Activities on the other hand, despite
working 100% of the time, will steal the focus of the current foreground
app, even though we are just doing some logging and showing a toast.
In addition, since stubs for hiding Magisk Manager is introduced, our
only communication method is left with the broadcast option, as
only broadcasting allows targeting a specific package name, not a
component name (which will be obfuscated in the case of stubs).
To make sure root requests will work on all devices, Magisk had to do
some experiments every boot to test whether broadcast is deliverable or
not. This makes the whole thing even more complicated then ever.
So lets take a look at another kind of component in Android apps:
ContentProviders. It is a vital part of Android's ecosystem, and as far
as I know no OEMs will block requests to ContentProviders (or else
tons of functionality will break catastrophically). Starting at API 11,
the system supports calling a specific method in ContentProviders,
optionally sending extra data along with the method call. This is
perfect for the native daemon to start a communication with Magisk
Manager. Another cool thing is that we no longer need to know the
component name of the reciever, as ContentProviders identify themselves
with an "authority" name, which in Magisk Manager's case is tied to the
package name. We already have a mechanism to keep track of our current
manager package name, so this works out of the box.
So yay! No more flaky broadcast tests, no more stupid OEMs blocking
broadcasts for some bizzare reasons. This method should in theory
work on almost all devices and situations.
In commit 8d4c407, native Magisk always launches an activity for
communicating with Magisk Manager. While this works extremely well,
since it also workaround stupid OEMs that blocks broadcasts, it has a
problem: launching an activity will claim the focus of the device,
which could be super annoying in some circumstances.
This commit adds a new feature to run a broadcast test on boot complete.
If Magisk Manager successfully receives the broadcast, it will toggle
a setting in magiskd so all future su loggings and notifies will always
use broadcasts instead of launching activities.
Fix#1412
For devices come with two /data mount points, magisk will bind the one in tmpfs and failed to load modules since this partition is empty.
Signed-off-by: Shaka Huang <shakalaca@gmail.com>
The root nodes are /system and /vendor. Adding new files into these
directories, although works on some devices, mostly bootloops on many
devices out there. So don't allow it, which also makes the whole magic
mounting logic much easier and extensible.
